1. Field of the Invention
The present invention relates to the field of angioplasty. In particular, the present invention relates to a dilatation balloon catheter.
2. Description of the Prior Art
Angioplasty has gained wide acceptance in recent years as an efficient and effective method for treating types of vascular diseases In particular, angioplasty is widely used for opening stenoses in the coronary arteries, although it is also used for treatment of stenoses in other parts of the vascular system.
The most widely used form of angioplasty makes use of a dilatation catheter which has an inflatable balloon at its distal end. Using fluoroscopy, the physician guides the catheter through the vascular system until the balloon is positioned across the stenosis. The balloon is then inflated by supplying fluid under pressure through an inflation lumen to the balloon. The inflation of the balloon causes stretching of the artery and pressing of the lesion into the artery wall to reestablish acceptable blood flow through the artery.
In order to treat very tight stenoses with small openings, there has been a continuing effort to reduce the profile of the catheter so that the catheter can reach and cross very tight stenoses. A successful dilatation catheter must also be sufficiently flexible to pass through tight curvatures through the very tortuous path of the vascular system. Still another requirement of the successful dilatation catheter is its "pushability". This involves the transmission of longitudinal force along the catheter from its proximal end to its distal end so that the physician can push the catheter through the vascular system and the stenosis.
Dilatation catheters can be divided into two groups: "over-the-wire" catheters and "non-over-the-wire" catheters. An over-the-wire catheter is one in which a guide wire lumen is provided so that the dilatation catheter can be fed over a guide wire until the balloon is positioned within the stenosis. A non-over-the-wire catheter acts as its own "guide wire". An advantage of a non-over-the-wire catheter is its potential for reduced profile because a guide wire lumen is not required.
The need for decreased dilatation catheter profile and increased flexibility has, in the past, required a compromise in the pushability and the torqueability of the catheter, particularly in the case of non-over-the-wire catheters. There is a continuing need for dilatation catheters of reduced catheter profile and improved flexibility without sacrificing torque response, catheter distal tip control, pushability of the catheter, and inflation/deflation times.